Ultrasonic surgical device and method for detection of attachment of ultrasonic probe

ABSTRACT

An ultrasonic surgical device includes a power source configured to generate power, an ultrasonic transducer electrically coupled to the power source and generating ultrasonic motion in response to the generated power, a sensor sensing current of the generated power supplied to the ultrasonic transducer, an ultrasonic probe mechanically couplable to the ultrasonic transducer, and a controller that receive a sensed current from the sensor, performs a frequency response analysis based on the sensed current, calculates a first resonant frequency and a first anti-resonant frequency of the transducer prior to coupling the ultrasonic probe based on the frequency response analysis, calculates a second resonant and second anti-resonant frequencies of the transducer based on the frequency response analysis prior to determining coupling to the ultrasonic transducer, and determines whether the ultrasonic probe is mechanically coupled to the ultrasonic transducer based on the first and second resonant and anti-resonant frequencies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/739,011 filed Jun. 15, 2015. The disclosure of the foregoingapplication is hereby incorporated by reference in its entirety herein.

BACKGROUND Technical Field

The present disclosure relates to an ultrasonic surgical device forverifying integrity of mechanical coupling between an ultrasonic probeand an ultrasonic transducer of the ultrasonic surgical device. Morespecifically, the present disclosure relates to an ultrasonic surgicaldevice configured to detect attachment of an ultrasonic probe to anultrasonic transducer.

Background of Related Art

Ultrasonic surgical devices have been demonstrated to provide hemostasisand efficient dissection of tissue with minimum lateral thermal damageand low smoke generation. Unlike electrosurgical devices, which requireelectrical current to flow through a patient, ultrasonic surgicaldevices operate by applying mechanical motion through an ultrasonicprobe using an ultrasonic transducer that is driven at a resonantfrequency. Thus, the ultrasonic surgical devices do not harm tissue dueto overexposure of electrical current being passed through the tissue.

However, when the ultrasonic transducer is not mechanically coupled orattached to the ultrasonic probe, the ultrasonic transducer cannotdeliver desired mechanical motion so as to obtain desired therapeuticeffects. Alternatively, absence of the ultrasonic probe may render theultrasonic device inoperable as the ultrasonic transducer would beincapable of generating sufficient mechanical motion at the resonantfrequency. Thus, there is a need for determining and analyzing thepresence or absence of the connection of the ultrasonic probe and theultrasonic transducer as well as for notifying a clinician of theabsence of the ultrasonic probe.

SUMMARY

The present disclosure provides ultrasonic surgical devices, whichinclude an ultrasonic transducer and an ultrasonic probe and areconfigured to analyze integrity of a mechanical coupling of theultrasonic probe to the ultrasonic transducer. The present disclosurealso provides a method for analyzing the connection between theultrasonic probe and the ultrasonic transducer.

The ultrasonic surgical device includes a power source configured togenerate power, an ultrasonic transducer electrically coupled to thepower source and configured to generate ultrasonic motion in response tothe generated power, a sensor configured to sense current of thegenerated power supplied to the ultrasonic transducer, an ultrasonicprobe configured to be mechanically couplable to the ultrasonictransducer, and a controller. The controller is configured to receivesensed current from the sensor, perform a frequency response analysisbased on the sensed current, calculate a first resonant frequency and afirst anti-resonant frequency of the transducer prior to coupling theultrasonic probe based on the frequency response analysis, calculate asecond resonant frequency and a second anti-resonant frequency of thetransducer based on the frequency response analysis prior to determiningwhether the ultrasonic probe is coupled to the ultrasonic transducer,and determine whether the ultrasonic probe is mechanically coupled tothe ultrasonic transducer based on the first and second resonantfrequencies and the first and second anti-resonant frequencies.

In an aspect, the controller is further configured to calculate a firstcoupling coefficient based on the first resonant frequency and the firstanti-resonance frequencies. The first coupling coefficient is calculatedusing a formula:

${k_{1}^{2} = {1 - \frac{f_{r1}^{2}}{f_{a1}^{2}}}},$where k₁ is the first coupling coefficient, f_(r1) is the first resonantfrequency, and f_(a1) is the first anti-resonant frequency.

In another aspect, the controller is further configured to calculate asecond coupling coefficient based on the second resonant frequency andthe second anti-resonance frequencies. The second coupling coefficientis calculated using a formula:

${k_{2}^{2} = {1 - \frac{f_{r2}^{2}}{f_{a2}^{2}}}},$where k₂ is the second coupling coefficient, f_(r2) is the secondresonant frequency, and f_(a2) is the second anti-resonant frequency.

In another aspect, the controller is further configured to determinewhether the ultrasonic probe is mechanically coupled to the ultrasonictransducer based on the first and second coupling coefficients. Thecontroller is further configured to determine whether the ultrasonicprobe is mechanically coupled to the ultrasonic transducer based on acomparison of a difference between the first and second couplingcoefficients with a predetermined threshold.

In another aspect, the sensed current has a maximum amplitude responseat the first resonant frequency and a minimum amplitude response at thefirst anti-resonant frequency in response to the ultrasonic probe notbeing mechanically coupled to the ultrasonic transducer.

In yet another aspect, the sensed current has a maximum amplituderesponse at the second resonant frequency and a minimum amplituderesponse at the second anti-resonant frequency in response to theultrasonic probe being mechanically coupled to the ultrasonictransducer.

The method for detecting a mechanical coupling between an ultrasonicprobe and an ultrasonic transducer of an ultrasonic surgical deviceincludes obtaining a first resonant frequency and a first anti-resonantfrequency of the ultrasonic transducer without the ultrasonic probebeing mechanically coupled to the ultrasonic transducer, detecting asecond resonant frequency and a second anti-resonant frequency of theultrasonic transducer prior to determining whether the ultrasonic probeis mechanically coupled to the ultrasonic transducer, calculating afirst coupling coefficient based on the first resonant frequency and thefirst anti-resonant frequency, calculating a second coupling coefficientbased the second resonant frequency and the second anti-resonantfrequency, and determining whether the ultrasonic probe is mechanicallycoupled to the ultrasonic transducer based on the first and secondcoupling coefficients.

In an aspect, obtaining the first resonant frequency and the firstanti-resonant frequency includes applying broadband alternating current(AC) signals to the ultrasonic transducer without the ultrasonic probebeing mechanically coupled to the ultrasonic transducer, sensing currentof the broadband AC signals supplied to the ultrasonic transducer,performing a frequency response analysis of the sensed current, anddetecting the first resonant frequency and the first anti-resonantfrequency based on the frequency response analysis. The sensed currenthas a maximum amplitude response at the first resonant frequency and aminimum amplitude response at the first anti-resonant frequency.

In another aspect, detecting a second resonant frequency and a secondanti-resonant frequency includes applying broadband alternating current(AC) signals to the ultrasonic transducer prior to determining whetherthe ultrasonic probe is mechanically coupled to the ultrasonictransducer, sensing current of the broadband AC signals supplied to theultrasonic transducer, performing a frequency response analysis of thesensed current, and detecting the second resonant frequency and thesecond anti-resonant frequency based on the frequency response analysis.The sensed current has a maximum amplitude response at the secondresonant frequency and a minimum amplitude response at the secondanti-resonant frequency.

In another aspect, the first coupling coefficient is calculated using aformula:

${k_{1}^{2} = {1 - \frac{f_{r1}^{2}}{f_{a1}^{2}}}},$wherein k₁ is the first coupling coefficient, f_(r2) is the firstresonant frequency, and f_(a2) is the first anti-resonant frequency.

In another aspect, the second coupling coefficient is calculated using aformula:

${k_{2}^{2} = {1 - \frac{f_{r2}^{2}}{f_{a2}^{2}}}},$where k₂ is the second coupling coefficient, f_(r2) is the secondresonant frequency, and f_(a2) is the second anti-resonant frequency.

In yet another aspect, determining whether the ultrasonic probe ismechanically coupled to the ultrasonic transducer further includescomparing a difference between the first and second couplingcoefficients with a predetermined threshold.

In an aspect, the method further includes displaying a message inresponse to the determination of whether the ultrasonic probe ismechanically coupled to the ultrasonic transducer.

In another aspect, the method further includes generating an optical oraudible signal in response to the determination of whether theultrasonic probe is mechanically coupled to the ultrasonic transducer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be understood by reference to theaccompanying drawings, when considered in conjunction with thesubsequent, detailed description, in which:

FIG. 1A is a side elevation view of an ultrasonic surgical device inaccordance with embodiments of the present disclosure;

FIG. 1B is a perspective view of parts separated, which shows the leftside of a handle, an ultrasonic transducer, and a right side of thehandle of the ultrasonic surgical device of FIG. 1A in accordance withembodiments of the present disclosure;

FIG. 2 is a side cross-sectional elevation view of an ultrasonicsurgical pen in accordance with embodiments of the present disclosure;

FIG. 3 is a block diagram of the ultrasonic surgical device of FIG. 1Ain accordance with embodiments of the present disclosure;

FIG. 4 is a circuit diagram illustrating a circuit model of anultrasonic transducer or an ultrasonic transducer connected to the probeof the ultrasonic surgical device of FIG. 1A in accordance withembodiments of the present disclosure;

FIG. 5 is a graphical illustration of frequency responses of currentflowing through an ultrasonic transducer in accordance with embodimentsof the present disclosure;

FIG. 6 is a block diagram illustrating coupling between the ultrasonictransducer and the ultrasonic probe of the ultrasonic surgical device ofFIG. 1A in accordance with embodiments of the present disclosure; and

FIG. 7 is a flow chart of a method for analyzing the connection betweenthe ultrasonic transducer and the ultrasonic probe in accordance withembodiments of the present disclosure.

DETAILED DESCRIPTION

Generally, the present disclosure provides an ultrasonic surgical devicefor detecting a defect in a connection between an ultrasonic transducerand an ultrasonic probe of an ultrasonic surgical device. The ultrasonictransducer is configured to generate ultrasonic mechanical motion at itsresonant frequency. The ultrasonic surgical device also includes aprocessor that is programmed to detect a mechanical coupling between theultrasonic transducer and the ultrasonic probe based on the changes inthe resonant frequency of the ultrasonic transducer.

A pulse-width modulation (PWM) amplitude control is employed to regulatethe mechanical motion of the ultrasonic probe and to provide differentlevels of power for treating tissue. Further, a proportional-integral(PI) controller is included to obtain a rapid transient response tochanges in load and to maintain stable surgical operations.

The ultrasonic surgical device also includes two control loops, whichmay be embodied in hardware and/or software executed by the processor,to control the ultrasonic mechanical motion of the ultrasonictransducer, which is energized by a DC power source. The first loop isan amplitude control loop configured to regulate the longitudinal modedisplacement and includes a closed-loop feedback control. The secondloop generates an AC signal from the DC power supplied to the ultrasonictransducer and automatically tracks the resonant frequency of theultrasonic transducer. The second control loop includes a band-passfilter oscillator. By using the first and second control loops, theultrasonic surgical device provides regulated ultrasonic mechanicalmotion at resonant frequency sufficient to treat tissue in accordancewith embodiments of this disclosure.

With reference to FIGS. 1A-1B, an ultrasonic surgical device 100 fortreating tissue is illustrated. The ultrasonic surgical device 100includes a power source 110, a housing 130, an ultrasonic transducer150, and an ultrasonic probe 190. The power source 110 provides DC powerto the ultrasonic transducer 150. In an aspect, the power source 110 maybe a battery that directly provides DC power. In a further aspect, thepower source 110 may be insertable or integrated into the housing 130 sothat the ultrasonic surgical device 100 may be portably carried withoutdisturbances of any cable. In yet another aspect, the power source 110may be rechargeable so that the power source 110 may be reusable.

In another aspect, the power source 110 may include a converter that isconnected to an alternating current (AC) power source and converts theAC power to DC power. The AC power source may be of a relatively lowfrequency, such as about 60 hertz (Hz), while the ultrasonic surgicaldevice 100 may operate at a higher frequency, such as 55.5 kilo hertz(kHz). Thus, the power source 110 may convert the low frequency AC powerto DC power so that the DC power may then be inverted to AC power havinga frequency suitable to cause the ultrasonic transducer 150 to generateultrasonic mechanical motion.

With continued reference to FIGS. 1A and 1B, the housing 130 includes ahandle portion 131 having a compartment 132, which houses the powersource 110, and a power source door 134 that secures the power source110 within the compartment 132. In an aspect, the power source door 134may be configured to form a water-tight seal between the interior andthe exterior of the compartment 132.

The housing 130 also includes a cover 133, which houses the ultrasonictransducer 150 and an output device 180. The ultrasonic transducer 150includes a generator assembly 152 and a transducer assembly 154, havinga transducer body 156 and a locking portion 162. The generator assembly152 is electrically coupled to the transducer assembly 154 via a pair ofcontacts 158.

With reference to FIG. 1B, the ultrasonic transducer 150 is illustratedas being separate from the cover 133. When the ultrasonic transducer 150is inserted into and assembled with the cover 133, the pair of contacts158 is connected to the round groove of the ultrasonic transducer 150 sothat the rotational movement of the transducer body 156 does not disruptthe connection between the transducer body 156 and the generatorassembly 152. Thus, the transducer body 156 is capable of freelyrotating within the housing 130.

The output device 180 outputs information about the ultrasonic surgicaldevice 100 or a status of the mechanical coupling between the ultrasonicprobe 190 and the ultrasonic transducer 150. The output device 180 mayalso display a warning that the ultrasonic probe 190 is not mechanicallycoupled to the ultrasonic transducer 150.

In another aspect, the output device 180 may be a speaker configured tooutput audible tones denoting no connection between the ultrasonic probe190 and the ultrasonic transducer 150. In yet another aspect, the outputdevice 180 may include one or more light emitting devices, configured toemit lights of various duration, pulses, and colors indicating thestatus of the mechanical coupling between the ultrasonic probe 190 andthe ultrasonic transducer 150.

The handle portion 131 further includes a trigger 136. When the trigger136 is actuated, the power source 110 provides energy to the ultrasonictransducer 150 so that the ultrasonic transducer 150 is powered togenerate ultrasonic mechanical motion of the ultrasonic probe 190. Asthe trigger 136 is released, the power supply to the ultrasonictransducer 150 is terminated.

The generator assembly 152 receives the DC power from the power source110 and generates AC signals having an ultrasonic frequency. Thegenerator assembly 152 may be capable of generating signals having afrequency based on a desired mode of operation, which may be differentfrom the resonant frequency of the ultrasonic transducer 150.

In an aspect, the generator assembly 152 may generate AC signals havinga relatively wide range of frequencies (e.g., broadband signals) or arelatively small range of frequencies (e.g., narrowband signals). Thebroadband AC signals may be used to detect a resonant frequency and ananti-resonant frequency of the ultrasonic transducer 150. Presence orabsence of the connection between the ultrasonic probe 190 and theultrasonic transducer 150 may be analyzed based on the resonant andanti-resonant frequencies as described in further detail below.

The transducer body 156 of the transducer assembly 154 receives the ACsignal generated by the generator assembly 152 and generates ultrasonicmechanical motion within the ultrasonic probe 190 based on the amplitudeand the frequency of the generated AC signal. The transducer body 156includes a piezoelectric material, which converts the generated ACsignal into ultrasonic mechanical motion. The transducer body 156 may bebased on an electrical oscillator model having an inductor and acapacitor, which oscillates between charging and discharging electricalenergy. This oscillation model for the transducer body 156 is describedfurther in detail below with respect to FIG. 4.

The ultrasonic surgical device 100 also includes a spindle 170, which iscoupled to the ultrasonic probe 190 and allows for rotation of theultrasonic probe 190 about its longitudinal axis. The ultrasonic probe190 is attached to the housing and is mechanically coupled to theultrasonic transducer 150 via the locking portion 162 such that as thespindle 170 is rotated about the longitudinal axis defined by theultrasonic probe 190, the ultrasonic probe 190 and the ultrasonictransducer 150 are also rotated correspondingly without affecting theconnection between the ultrasonic transducer 150 and the ultrasonicprobe 190. Additionally, as the spindle 170 is rotated, the ultrasonictransducer 150 may be also rotated along with the ultrasonic probe 190.

FIG. 1B illustrates the ultrasonic transducer 150 separated from thehandle portion 131 of the housing 130 of FIG. 1A. The ultrasonictransducer 150 includes a slidable first connector 164 and the handleportion 131 of the housing 130 includes a second connector 142configured and dimensioned to engage the slidable first connector 164allowing for selective engagement of the ultrasonic transducer 150 withthe handle portion 131.

The locking portion 162 physically and/or mechanically locks theultrasonic probe 190 to the ultrasonic transducer 150. The lockingportion 162 maintains physical contact between the ultrasonic probe 190and the transducer body 156 as the ultrasonic probe 190 is rotated. Thelocking portion 162 conveys the ultrasonic mechanical motion from thetransducer body 156 to the ultrasonic probe 190 without losing theconnection. In an aspect, the locking portion 162 may be a maleconnector and the ultrasonic probe 190 may include a counterpart femaleconnector.

The ultrasonic probe 190 may include an end effector suitable forsealing tissue. The ultrasonic probe 190 includes a waveguide 192, ablade 194 extending from the waveguide 192, and a jaw member 196. Theultrasonic probe 190 is mechanically coupled to the transducer body 156via the locking portion 162.

The jaw member 196 may be formed as a pivoting arm configured to graspand/or clamp tissue between the jaw member 196 and the blade 194. Whenthe jaw member 196 and the blade 194 grasp tissue and the blade 194conveys the ultrasonic mechanical motion, temperature of the graspedtissue between the blade 194 and the jaw member 196 increases due to theultrasonic mechanical motion. This motion in turn treats, e.g., cutsand/or seals, tissue.

In instances when the ultrasonic probe 190 is not attached to theultrasonic transducer 150, the ultrasonic mechanical motion generated bythe ultrasonic transducer 150 cannot be delivered to the ultrasonicprobe 190. As a result, the ultrasonic surgical device 100 cannot beused to treat the tissue. The ultrasonic surgical device 100 accordingto the present disclosure is configured to determine whether or not theultrasonic probe 190 is mechanically coupled to the ultrasonictransducer 150 to ensure operations of the ultrasonic probe 190.

FIG. 2 shows an ultrasonic surgical pen 200, which is anotherillustrative embodiment of the ultrasonic surgical device 100 of FIG.1A. The ultrasonic surgical pen 200 includes a power source 210, thehousing 230, the ultrasonic transducer 250, and the ultrasonic probe290. The power source 210, the housing 230, and the ultrasonictransducer 250 of the ultrasonic surgical pen 200 are substantiallysimilar to the power source 110, the housing 130, and the ultrasonictransducer 150 of the ultrasonic surgical device 100, respectively. Theultrasonic probe 290 may be an ultrasonic cauterizer. The shape anddimensions of the housing 230 of the ultrasonic surgical pen 200 alsoprovide for a different ergonomic option than the ultrasonic surgicaldevice 100.

FIG. 3 illustrates a block diagram of the ultrasonic surgical device 100using a band-pass filter (BPF) oscillator architecture, which tracks theresonant frequency of the BPF regardless of process variations andenvironmental interferences. A pulse-width modulation (PWM) signal isused to regulate ultrasonic mechanical motion as described in furtherdetail below.

The ultrasonic surgical device 100 includes the power source 110, anamplitude controller 320, and a resonance tracking controller 360. Theamplitude controller 320 includes a converter 330, a sensor 340 and acontroller 350. The resonance tracking controller 360 includes anon-resonant inverter 370, the ultrasonic transducer 150, and acomparator 390.

The power source 110 provides DC power to the amplitude controller 320,which controls amplitude of the output of the amplitude controller 320so that ultrasonic surgical device 100 generates ultrasonic mechanicalmotion suitable for treating tissue. In an aspect, when the DC power isprovided, the converter 330 amplifies the amplitude of the DC power. Theconverter 330 may be a buck converter or a step-down converter. Thesensor 340 then senses current flowing to the resonance trackingcontroller 360. The controller 350 receives the sensed results from thesensor 340 and generates a digital pulse width modulated (PWM) controlsignal to control a duty cycle of the converter 330.

The resonant tracking controller 360 is configured to generateultrasonic motion at a frequency substantially equal to the resonantfrequency of the ultrasonic transducer 150. In an aspect, thenon-resonant inverter 370 receives the amplified DC power from theconverter 330 and inverts to AC power having a first frequency. Thenon-resonant inverter 370 is driven by output signals from thecomparator 390. The comparator 390 adjusts the frequency of the AC powerfrom an initial (e.g., first) frequency until the frequency issubstantially equal to the resonant frequency of the ultrasonictransducer 150. The non-resonant inverter 370 may include any suitableelectrical topology such as an H-bridge (e.g., full bridge), a halfbridge, and the like.

In an aspect, the output signals from the comparator 390 may bedigitally generated by the controller 350. The controller 350 may be aprogrammable gate array (PGA), field-programmable gate array (FPGA),application-specific integrated circuit (ASIC), complex programmablelogic device (CPLD), or any other suitable logic device.

The controller 350 also generates PWM control signals to drive theconverter 330 and resonant control signals for the non-resonant inverter370. The controller 350 receives outputs from the comparator 390 andgenerates resonant signals for the non-resonant inverter 370 in responseto the output of the comparator 390. The non-resonant inverter 370 theninverts the DC power to the AC signal, whose frequency is independent ofthe switching frequency of the non-resonant inverter 370, by trackingthe resonant frequency of the ultrasonic transducer 150.

In an aspect, a transformer (not shown) may be electrically coupledbetween the non-resonant inverter 370 and the ultrasonic transducer 150so that the transformer may increase or decrease the amplitude of theinverted AC power to a desired level.

The ultrasonic transducer 150 receives the AC power having a firstfrequency and generates ultrasonic mechanical motion. In a case when thefrequency of the AC signals is different from the resonant frequency ofthe ultrasonic transducer 150, ultrasonic mechanical motion generated bythe ultrasonic transducer 150 may not be optimal for intended purposes.The comparator 390 is configured to track the resonant frequency of theultrasonic transducer 150 to cause the frequency of the AC signal tomatch the resonant frequency of the ultrasonic transducer 150 to providefor optimal operation of the ultrasonic transducer 150.

In an aspect, the resonance tracking controller 360 may include aresonant inverter (not shown) connected to the ultrasonic transducer 150without the non-resonant inverter 370 and the comparator 390. Theresonant inverter may be configured to invert the amplified DC signalsand generate AC signal having a frequency substantially equal to theresonant frequency of the ultrasonic transducer 150.

In an aspect, the resonant tracking controller 360 may be used to detecta resonant frequency of the ultrasonic transducer 150. The sensor 340 isconfigured to sense voltage and current of the broadband AC signalsapplied to the ultrasonic transducer 150 and transmit the sensor signalsto the controller 350. The controller 350 digitally processes the sensorsignals and monitors the voltage and current values. Further, thecontroller 350 performs frequency response analysis (e.g., Fouriertransformation, digital Fourier transformation, or other frequencyrelated analysis) to identify amplitude response with respect tofrequencies of the current. The resonant frequency of the ultrasonictransducer 150 may be a frequency at which the amplitude response of thecurrent is the maximum and the anti-resonant frequency of the ultrasonictransducer 150 may be a frequency at which the amplitude response of thecurrent is the minimum.

FIG. 4 shows electrical circuit models 400 and 450 of the ultrasonictransducer 150 of FIG. 1A in accordance with embodiments of the presentdisclosure. The electrical circuit model 400 or 450 model resonant oranti-resonant behavior of the ultrasonic transducer 150. The electricalcircuit model 400 is a series resistor-inductor-capacitor (RLC) circuitincluding a resistor 410, a capacitor 420, and an inductor 430, which isconnected in parallel with another capacity 440.

The resonant frequency f_(r) of the circuit 400 is calculated usingformula (I) below:

$\begin{matrix}{{f_{r} = \frac{1}{2\pi\sqrt{L_{1} \cdot C_{1}}}},} & (I)\end{matrix}$where L₁ is the inductance of the inductor 430 and C₁ is the capacitanceof the capacitor 420. Based on the circuit 400, the inductance and thecapacitance of the ultrasonic transducer 150 determines the resonantfrequency of the ultrasonic transducer 150.

The ultrasonic transducer 150 converts electrical energy into mechanicalmotion fully at the resonant frequency of the ultrasonic transducer 150.In other words, when the ultrasonic transducer 150 is operated at afrequency different from the resonant frequency, the ultrasonictransducer 150 does not operate optimally. Further, when the ultrasonicprobe 190 is not mechanically coupled to the ultrasonic transducer 150,the ultrasonic probe 190 cannot deliver the ultrasonic motion to tissuefor intended therapeutic purposes and the ultrasonic transducer 150 maymaintain its resonant frequency and anti-resonant frequency.

In an aspect, the resonant frequency of the ultrasonic transducer 150 orthe ultrasonic probe 190 may be obtained by testing and/or duringmanufacturing. In another aspect, the resonant frequencies may bemeasured and calculated or identified by the controller 350 of theultrasonic surgical device 100. Determination of the resonant frequencymay be accomplished using the comparator 390 with the non-resonantinverter 370, which can track the resonant frequency. The non-resonantinverter 370 may apply AC signals at a single frequency to theultrasonic transducer 150 for a predetermined time and the comparator390 may then track the frequency of the electrical energy until theresonant frequency is identified. The resonant frequency of theultrasonic probe 190 may also be identified or measured using othertechniques known in the related art.

In another aspect, when a broadband frequency AC signal is provided tothe ultrasonic transducer 150, the controller 350 performs frequencyresponse analysis and identifies the resonant frequency at which thefrequency response is the maximum and the anti-resonant frequency atwhich the frequency response is the minimum.

When a voltage source is connected to the circuit 400, due to thepotential difference, a current flows through the circuit 400. Then, theanti-resonant frequency f_(a) of the 400 is calculated by:

$\begin{matrix}{{f_{a} = \frac{1}{2\pi\sqrt{L_{1} \cdot \left( \frac{C_{1} \cdot C}{C_{1} + C} \right)}}}.} & ({II})\end{matrix}$This frequency f_(a) is an anti-resonant frequency because the frequencyresponse is the minimum at the anti-resonant frequency f_(a), when theelectrical impedance of the ultrasonic transducer 150 is the maximum.

FIG. 5 shows a frequency response graph 500 illustrating amplituderesponses of current in frequency domain, which flows through theultrasonic surgical device 100 in accordance with embodiments of thepresent disclosure. FIG. 5 also illustrates frequency responses at theresonant frequency f_(r) and the anti-resonant frequency f_(a). Thevertical axis 510 of the frequency response graph 500 representsamplitudes of current passing through an ultrasonic transducer 150 ofthe ultrasonic surgical device 100 and the horizontal axis 520 of thefrequency response graph 500 represents frequencies of the current. Whenbroadband AC signals are applied to the ultrasonic transducer 150, afrequency response curve 530 may be obtained by the controller 350 ofthe ultrasonic surgical device 100. As shown in the frequency responsecurve 530, the amplitude of the current has the maximum value at a firstfrequency 540 and the minimum value at a second frequency 550. The firstfrequency 540 corresponds to the resonant frequency f_(r) of theultrasonic transducer 150 and the second frequency 550 corresponds tothe anti-resonant frequency f_(a) of the ultrasonic transducer 150.

The ultrasonic transducer 150 by itself or a combined body of theultrasonic transducer 150 and the ultrasonic probe 190 exhibit differentresonant and the anti-resonance frequencies. Thus, presence or absenceof the ultrasonic probe 190 can be detected based on the resonant andanti-resonance frequencies. This will be further described below withrespect to FIG. 7.

FIG. 6 shows a block diagram 600 illustrating a connected state of theultrasonic transducer 150 and the ultrasonic probe 190. The resonant andanti-resonant frequencies of the connected body 610 depend uponmechanical coupling between the ultrasonic probe 190 and the ultrasonictransducer 150. When the ultrasonic probe 190 is not mechanicallycoupled to the ultrasonic transducer 150, the connected body 610 mayhave resonant and anti-resonant frequencies similar to those of theultrasonic transducer 150 not being coupled to the ultrasonic probe 190.When the ultrasonic probe 190 is mechanically coupled to the ultrasonictransducer 150, the connected body 610 will have resonant and/oranti-resonant frequencies different to those of the ultrasonictransducer 150.

The present disclosure utilizes coupling coefficients, which may be usedto determine mechanical coupling between the ultrasonic transducer 150and the ultrasonic probe 190. A first coupling coefficient k₁ isrepresentative of the ultrasonic probe 190 being absent from theultrasonic surgical device 100 or not being mechanically coupled to theultrasonic transducer 150. The first coupling coefficient k₁ iscalculated by:

$\begin{matrix}{{k_{1}^{2} = {1 - \frac{f_{r\; 1}^{2}}{f_{a\; 1}^{2}}}},} & ({III})\end{matrix}$where f_(r1) is the resonant frequency and f_(a1) is the anti-resonantfrequency of the ultrasonic transducer 150.

A second coupling coefficient k₂ is representative of the ultrasonicprobe 190 being present in the ultrasonic surgical device 100 or beingmechanically coupled to the ultrasonic transducer 150. In the same way,second coupling coefficient k₂ is calculated by:

$\begin{matrix}{{k_{2}^{2} = {1 - \frac{f_{r\; 2}^{2}}{f_{a\; 2}^{2}}}},} & ({IV})\end{matrix}$where f_(r2) is the resonant frequency and f_(a2) is the anti-resonantfrequency of the combined body 610.

When the second coupling coefficient k₂ differs significantly from thefirst coupling coefficient k₁, the ultrasonic probe 190 is determined tobe present in the ultrasonic surgical device 100 or mechanically coupledto the ultrasonic transducer 150. After it is determined that theultrasonic probe 190 is mechanically coupled to the ultrasonictransducer 150, it may be further determined whether or not theultrasonic probe 190 is properly mechanically coupled to the ultrasonictransducer 150. Details of this determination may be found in a commonlyassigned U.S. patent application Ser. No. 15/161,451, now U.S. Pat. No.10,342,568, entitled “Ultrasonic Surgical Device and Method ForDetection of Attachment of Ultrasonic Probe,” the entire contents ofwhich are incorporated by reference herein. Conversely, when the secondcoupling coefficient k₂ is substantially the same as the first couplingcoefficient k₁, the ultrasonic probe 190 is absent in the ultrasonicsurgical device 100.

FIG. 7 shows a method 700 for determining presence or absence of theultrasonic probe 190 in the ultrasonic surgical device 100 in accordancewith embodiments of the present disclosure. At step 710, a firstresonant frequency and a first anti-resonant frequency of the ultrasonictransducer 150 are obtained, when the ultrasonic probe 190 is notcoupled to the ultrasonic transducer 150. The first resonant andanti-resonant frequencies of the ultrasonic transducer 150 may beobtained in a manner described above.

In an aspect, first resonant and anti-resonant frequencies may beobtained from applying broadband AC signals to the ultrasonic transducer150. A sensor of the ultrasonic surgical device 100 senses the broadbandAC signals passing through the ultrasonic transducer 150 and transmitsto a controller 350. The sensed results may be digitally sampled andthen transmitted to the controller 350, which then performs frequencyresponse analysis on the sensed results. The controller 350 may set afrequency, at which the amplitude response of the current is themaximum, as the first resonant frequency and set a frequency, at whichthe amplitude of the current is the minimum, as the first anti-resonantfrequency.

In step 720, the controller 350 may calculate the first couplingcoefficient k₁ using the formula (III) above. In step 730, before it isdetermined or when it is unknown whether or not the ultrasonic probe 190is mechanically coupled to the ultrasonic transducer 150, the broadbandAC signals are applied to the ultrasonic transducer 150. As noted above,the bandwidth of the broadband AC signals has a wide range offrequencies sufficient to include the first resonant and firstanti-resonant frequencies.

In step 735, the sensor 340 senses the voltage and current of theapplied broadband AC signals and transmits the measurements to thecontroller 350. As described above, the sensed results may be digitallysampled. The controller 350 performs frequency response analysis on thesensed results in step 740.

In step 745, the controller 350 calculates a second resonant frequencyas a frequency at which the amplitude of the current is at its maximumbased on the frequency response analysis and calculates a secondanti-resonant frequency as a frequency at which the amplitude responseof the current is at its the minimum.

In step 750, the controller 350 may calculate the second couplingcoefficient k₂ using the formula (IV) above. The controller 350 alsocalculates a difference between the first and second couplingcoefficients in step 760. The difference is compared with apredetermined threshold in step 770 to determine if there is asubstantial difference between coupling coefficients, which isindicative of the ultrasonic probe 190 being attached to the ultrasonictransducer 150. When it is determined that the difference is less thanthe predetermined threshold, in step 780, a message is displayed toindicate that the ultrasonic probe 190 is absent in the ultrasonicsurgical device 100 or is not mechanically coupled to the ultrasonictransducer 150.

When it is determined that the difference is greater than or equal tothe predetermined threshold in step 770, in step 790, a message isdisplayed to indicate that the ultrasonic probe 190 is present in theultrasonic surgical device 100 or is mechanically coupled to theultrasonic transducer 150. By displaying a message in step 780 or 790,the method 700 for determining presence or absence of the ultrasonicprobe 190 is ended.

In an aspect, when the message indicates that the ultrasonic probe 190is absent in the ultrasonic surgical device 100 or is not mechanicallycoupled to the ultrasonic transducer 150 in step 780, a clinician usingthe ultrasonic surgical device 100 may connect the ultrasonic probe 190with the ultrasonic transducer 150 so that the clinician can use theultrasonic surgical device 100 to perform operations.

Since other modifications and changes may be made to fit particularoperating requirements and environments, it is to be understood by oneskilled in the art that the present disclosure is not limited to theillustrative examples described herein and may cover various otherchanges and modifications which do not depart from the spirit or scopeof this disclosure.

What is claimed is:
 1. An ultrasonic surgical device comprising: anultrasonic transducer configured to generate ultrasonic motion inresponse to current supplied from a power source; an ultrasonic probeconfigured to be couplable to the ultrasonic transducer; and acontroller configured to: perform a frequency response analysis based onthe current supplied to the ultrasonic transducer; calculate a firstresonant frequency and a first anti-resonant frequency of the ultrasonictransducer based on the frequency response analysis prior to couplingthe ultrasonic probe to the ultrasonic transducer; calculate a secondresonant frequency and a second anti-resonant frequency of theultrasonic transducer based on the frequency response analysis aftercoupling the ultrasonic probe to the ultrasonic transducer; anddetermine whether the ultrasonic probe is properly coupled to theultrasonic transducer based on the first and second resonant frequenciesand the first and second anti-resonant frequencies.
 2. The ultrasonicsurgical device according to claim 1, wherein the controller isconfigured to calculate a first coupling coefficient based on the firstresonant frequency and the first anti-resonant frequency.
 3. Theultrasonic surgical device according to claim 2, wherein the firstcoupling coefficient is calculated based on formula (I): $\begin{matrix}{{k_{1}^{2} = {1 - \frac{f_{r\; 1}^{2}}{f_{a\; 1}^{2}}}},} & (I)\end{matrix}$ where k₁ is the first coupling coefficient, f_(r1) is thefirst resonant frequency, and f_(a1) is the first anti-resonantfrequency.
 4. The ultrasonic surgical device according to claim 3,wherein the controller is configured to calculate a second couplingcoefficient based on the second resonant frequency and the secondanti-resonant frequency.
 5. The ultrasonic surgical device according toclaim 4, wherein the second coupling coefficient is calculated based onformula (II): $\begin{matrix}{{k_{2}^{2} = {1 - \frac{f_{r2}^{2}}{f_{a2}^{2}}}},} & ({II})\end{matrix}$ where k₂ is the second coupling coefficient, f_(r2) is thesecond resonant frequency, and f_(a2) is the second anti-resonantfrequency.
 6. The ultrasonic surgical device according to claim 5,wherein the controller is configured to determine whether the ultrasonicprobe is properly coupled to the ultrasonic transducer based on thefirst and second coupling coefficients.
 7. The ultrasonic surgicaldevice according to claim 6, wherein the controller is configured todetermine whether the ultrasonic probe is properly coupled to theultrasonic transducer based on a comparison of a difference between thefirst and second coupling coefficients with a predetermined threshold.8. The ultrasonic surgical device according to claim 1, furthercomprising: a sensor configured to sense current supplied to theultrasonic transducer.
 9. The ultrasonic surgical device according toclaim 8, wherein the current has a maximum amplitude response at thefirst resonant frequency and a minimum amplitude response at the firstanti-resonant frequency.
 10. The ultrasonic surgical device according toclaim 8, wherein the current has a maximum amplitude response at thesecond resonant frequency and a minimum amplitude response at the secondanti-resonant frequency.
 11. A method for detecting a proper couplingbetween an ultrasonic probe and an ultrasonic transducer of anultrasonic surgical device, the method comprising: performing a firstfrequency response analysis based on current supplied to an ultrasonictransducer prior to coupling an ultrasonic probe to the ultrasonictransducer; calculating a first resonant frequency and a firstanti-resonant frequency of the ultrasonic transducer based on the firstfrequency response analysis; performing a second frequency responseanalysis based on current supplied to the ultrasonic transducer aftercoupling the ultrasonic probe to the ultrasonic transducer; calculatinga second resonant frequency and a second anti-resonant frequency of theultrasonic transducer based on the second frequency response analysis;and performing a determination whether the ultrasonic probe is properlycoupled to the ultrasonic transducer based on the first and secondresonant frequencies and the first and second anti-resonant frequencies.12. The method according to claim 11, wherein the current is a broadbandalternating current signal.
 13. The method according to claim 11,wherein the current supplied to the ultrasonic transducer has a maximumamplitude response at the first resonant frequency and a minimumamplitude response at the first anti-resonant frequency.
 14. The methodaccording to claim 11, further comprising: calculating a first couplingcoefficient based on the first resonant frequency and the firstanti-resonant frequency; and wherein the first coupling coefficient iscalculated based on formula (I): $\begin{matrix}{{k_{1}^{2} = {1 - \frac{f_{r1}^{2}}{f_{a1}^{2}}}},} & (I)\end{matrix}$ wherein k₁ is the first coupling coefficient, f_(r1) isthe first resonant frequency, and f_(a1) is the first anti-resonantfrequency.
 15. The method according to claim 14, wherein the currentsupplied to the ultrasonic transducer has a maximum amplitude responseat the second resonant frequency and a minimum amplitude response at thesecond anti-resonant frequency.
 16. The method according to claim 14,further comprising: calculating a second coupling coefficient based thesecond resonant frequency and the second anti-resonant frequency; andwherein the second coupling coefficient is calculated based on formula(II): $\begin{matrix}{{k_{2}^{2} = {1 - \frac{f_{r2}^{2}}{f_{a2}^{2}}}},} & ({II})\end{matrix}$ where k₂ is the first coupling coefficient, f_(r2) is thesecond resonant frequency, and f_(a2) is the second anti-resonantfrequency.
 17. The method according to claim 16, wherein the currentsupplied to the ultrasonic transducer has a maximum amplitude responseat the second resonant frequency and a minimum amplitude response at thesecond anti-resonant frequency.
 18. The method according to claim 16,wherein performing the determination of whether the ultrasonic probe ismechanically coupled to the ultrasonic transducer includes comparing adifference between the first and second coupling coefficients with athreshold.
 19. The method according to claim 11, further comprisingdisplaying a message in response to the determination of whether theultrasonic probe is mechanically coupled to the ultrasonic transducer.20. The method according to claim 11, further comprising generating anoptical or audible signal in response to the determination of whetherthe ultrasonic probe is properly coupled to the ultrasonic transducer.